The Personal Breathalyzer is probably a good idea..

How drunk are you actually? It’s always a fraught question after a night at the pub. And if it involves you driving home afterwards, it’s not one that’s best solved by proving you can walk in a straight line while reciting the alphabet backwards. Perhaps an accurate gadget might be more useful.

And that’s exactly what etailers EFO are selling – a personalised breathalyzer which according to them is the most effective and scientific way to check up the blood-alcohol levels.

Of course it’s always safer not to drink at all if you’re driving. but if you’re toeing a fine line then this little breath-testing gadge could be very useful.

You exhale into a “vent” to get your reading which pops up 20 seconds later. Unfortunately you don’t get the exact figure – but one of three lights flicks on: Green: under 0.02% Blood Alchol Content (BAC); Yellow: for over 0.02% BAC; and Red: for over 0.05% BAC.

And if you’ve wondered how something you drank an hour ago can be in the air you breathe out two hours later, HowStuffWorks explains how it goes from your blood stream to your breath, in short, it evaporates out of tiny blood vessels in your lungs:

“As the blood goes through the lungs, some of the alcohol moves across the membranes of the lung’s air sacs (alveoli) into the air, because alcohol will evaporate from a solution — that is, it is volatile. The concentration of the alcohol in the alveolar air is related to the concentration of the alcohol in the blood. As the alcohol in the alveolar air is exhaled, it can be detected by the breath alcohol testing device. Instead of having to draw a driver’s blood to test his alcohol level, an officer can test the driver’s breath on the spot and instantly know if there is a reason to arrest the driver.”

Now you know. Judging from the English grammar levels on the site, efo doesn’t sound like the most polished online retailer – but for £7.80, this little gadget could be worth a try and they take payments over paypal.